We live in sw France
A little pruning should enourage more fullness at the bottom. Here is an article on how to prune Rose of Sharon. It also discusses rejuvenation pruning if it needs a severe cut.
https://www.gardeningknowhow.com/ornamental/shrubs/rose-of-sharon/pruning-rose-of-sharon.htm
the bulb is inside in 4-6 hrs bright sun
I'm not sure if you really mean hibiscus since they grow from seed. Could it be an Amaryllis bulb you have? If so, here are aftercare instructions following the bloom cycle.
I am getting ready to prune my hardy hibiscus and am not sure how to do it. Do I take the whole thing to the ground or just trim back the branches?
This depends on the age of the shrub. If it is very old, and getting unmanageable, then you can prune it to the ground. If this is a young, and productive, shrub, then only prune what is completely dead.
Here is an article that will help:
what is causing this and how to treat?
This could be fertilizer burn from applying too much fertilizer. Try backing off the fertilizer applications. It also can be caused by dry soil. Fungal leaf spot is another possibility. Here is more:
https://www.gardeningknowhow.com/plant-problems/disease/plant-leaf-spots.htm
My hibiscus plant started to have yellow leaves about two weeks ago. All winter it was fine. It has been in a southern window and I feed and water only when needed. It is still giving me buds which have been blooming one a day until this occurred.
Here's an article that should help:
https://www.gardeningknowhow.com/plant-problems/environmental/plant-leaves-turn-yellow.htm
Check on your growing conditions here: https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm
Leaves are curling and look eaten on edges. What can of insect spray can I use? I do not see aphids but can't determine what type of "bug" it might be.
See if any of these pests concur with damage:
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/pests-on-hibiscus-plants.htm
Hi I live in Toronto Canada, my hibiscus all the branches were dead but the trunk bark when I scratched it’s still green I was told by a friend to cut all the branches The first picture is the current after I cut it Second it when it was loosing the leafs and branches were dying 3rd picture when it was blooming Do I have to do anything now or is it dying Thanks for your help.
Pruning it should promote new growth, so I would wait and see if new shoots develop. As soon as it's frost free you can set it back outside.